High-field dark currents in thin CVD silicon nitride with graded interfacial composition

Abstract
Ellipsometric measurements of thin CVD Si3N4 films deposited on Si reveal a graded composition of silicon oxynitride with increasing oxygen content as the Si‐Si3N4 interface is approached. Measurements of steady‐state dark currents, injected into Si3N4 from negatively biased Al contacts at constant average field, Eav=Vτ−1=6 MV/cm, have been fitted to an empirical relation, J=J0 exp(τ0/τ), where τ is the film thickness and τ0=1039 Å. Increased film conductivity with decreasing thickness τ is attributed to diminished electron trapping as τ approaches the centroid of trapped charge, δ∼100 Å.